Hydraulic hammers are used at work sites to break up large and hard objects such as rocks and concrete before such objects can be moved away. Generally, hydraulic hammers are coupled to a machine, such as excavators or other machines. The hydraulic hammers are powered by a combination of hydraulic power and pneumatic power. The hydraulic hammers are provided with a reservoir/cartridge for supplying lubricants such as grease, to bearing surfaces in the hydraulic hammer so as to reduce friction between the moving parts. The hydraulic hammier and the cartridge are provided with a glass window so as to allow an operator to monitor the level of grease within the cartridge. However, at times, the operator may fail to do so and fail to observe that the cartridge is empty. In such situations air is pumped into the moving parts of the hydraulic hammer and may cause the hydraulic hammer to operate inefficiently.
U.S. Pat. No. 6,145,625 hereinafter referred as the '625 patent, describes a grease lubricator for construction machine is provided. The lubricator for delivering grease lubricant to lubricating locations of a machine is coupled to a grease container and has a work chamber in which a delivery piston reciprocates. To ensure that a compressible medium, such as air which has been drawn into the work chamber is rapidly expelled therefrom, the work chamber is divided by a grease return device into a compressing portion and a delivery portion. Triggered by a sufficiently high pressure level which prevails in the compressing portion and which is present only during grease delivery, an otherwise blocked return connection is established between the compressing portion and a supply port which couples the grease container to the work chamber, as long as the head of the delivery piston, in the course of its grease delivery stroke (forward stroke) is situated in the compressing portion. However, the '625 patent may not expel the air which enters through the lubricator.